Adjustable precision electromechanical timer



April 29, 1958 l. w. DOYLE ,ETAL 2,832,854

ADJUSTABLE PRECISION ELECTROMECHANICAL TIMER Original Filed March 5.1953 7 slbfi TO 4 SHUAI'TER SHUTTER 'llllllllllll lyllxllIIIIIIIIIIIilI/IIIIlb UnitedStates Patent v Patented Apr. 29,195

ADJUSTABLE PRECISION ELECTRO- MECHANICAL TIMER Irving W. Doyle,Massapequa, and Clayton W. Hougliton, Westbury, N. Y., assignors toFair-child Camera and Instrument Corporation, a corporation of DelawareOriginal application March 5 1953 Serial No. 340,557.

Divided and this application Sepiember 21, 1953, Serial No. 381,263

Claims. (Cl. 200-24) This invention relates to adjustable precisionelectromechanical timers and, while it is of general application, it isparticularly adapted for timing the successive operations of thesections of a two-section camera shutter.

This application is a division of copending application, Serial No.340,557, filed March 5, 1953, entitled Shutter-Actuating Mechanism forCameras.

In certain timing applications, such as the timing of the sections of atwo-section camera shutter, it is desired to develop in response to asingle tripping or triggering action two electrical pulses having a verysmall but precisely determined time spacing adjustable over a relativewide range of values. In such a camera application, these two spacedpulses are then utilized independently to energize the actuatingelements of the sections of the shutter in rapid sequence, the timespacing between the pulses determining the exposure time of the shutter.

Electromechanical timers of the prior art for determining very short butadjustable time intervals have generally relied upon either anescapement mechanism or a damping vane or equivalent rotatable in adamping medium, such as air. It has been found that the accuracy of suchtimers tends to vary considerably with variations in their environment,such as variations in ambient temperature. In addition, such timersusually have a considerably lower percentage accuracy over the portionof their operating range providing minimum time intervals. In'general,they are also, difficult to adjust over a wide range of timingintervals.

It is an object of the present invention, therefore, to provide anew andimproved adjustable precision electromechanical timer which obviates oneor more of the foregoing disadvantages of prior electromechanicaltimers.

It is another object of the invention to provide a new and improvedadjustable precision electromechanical timer which has a high degree ofrelative accuracy of timing intervals approximately uniform over itsnormal range of adjustment.

It is a further object of the invention to provide a new and improvedadjustable precision electromechanical timer which is readily adjustableover a relatively wide range of timing intervals.

It is a further object of the invention to provide a new and improvedadjustable precision electromechanical timer which maintains a highdegree of accuracy notwithstanding substantial variations in ambienttemperature or other factors of environment.

In accordance with the invention, a precision electromechanical timerfor developing a pair of electrical pulses adjustably spaced in timecomprises first electric contact means and second electric contact meansco-operating with the first contact means and relatively movable withrespect thereto, one of such contact means including a pair of spacedcontacts. The timer also includes means for imparting a predeterminedacceleration to the relatively movable contact means for developingtime-spaced electrical pulses, and means throughout the range ofrelative movement for adjusting the spacing of the pair trical pulses.

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the followingdescription taken in connection with the accompanying drawing, while itsscopewill be pointed out in the appended claims.

The single figure of the drawing is an exploded perspec? tive view of aprecision electromechanical timer embodying the invention andcorresponding to that illustrated in Fig. 2 of aforesaid copendingapplication, Serial No. 340,557, to which certain of the circuitconnections of Fig. 1 of said application have been added for the sakeof completeness.

Referring now to the drawing, there is illustrated a precisionelectromechanical timer for developing in response to a single trippingor triggering action a pair of electrical pulses adjustably spaced intime. This timer includes a normally latched biased inertia member whichmay be in the form of a rotatable inertia disc or wheel mounted on ashaft 46 and having a projecting arm 47 normally engaged by a latch 48mounted on a pivot 49 extending from a frame member 50 and biased intoengagement with the arm 47 by a spring 51 for restraining the inertiamember 45. The latch 48 has a pro jecting tailpiece 52 for use inreleasing the latch, as described hereinafter. The inertia wheel 45 isbiased for rotation in a counterclockwise direction by means of a spiralspring 53, the inner end of which is secured to a shaft 54 and the outerend of which is secured to a cup-shaped retaining element 55 withinwhich the spring 53 is housed. The end of the retainer 55 is closed by aretaining plate 56.

There is provided a rotatable armature electromagnet 57 for initiallywinding the spring 53-and then releasing the latch 48 and the inertiawheel 45 to impart a pre-i determined acceleration thereto under theinfluence of its biasing spring 53 to effect an exposure and subse*quently to reset the wheel 45. The electromagnet 57 is provided with arotary armature 58 biased into the po-- sition illustrated by aninternal spring (not shown) and,

upon energization, rotatable in a counterclockwise direction, asindicated by the arrow. The armature 58 drives the shaft 54 to windspring 53 and includes an axially extending arm 58a which serves as astop for an adjustable stop screw 59 extending from the inertia.

wheel 45, the elements 581:, 59 serving to limit the counterclockwisemovement of the wheel 45 under the in-.

fluence of its biasing spring 53. Extending from the armature 58 is atrip arm 58b disposed upon rotation? to engage the upper surface of thetail-piece 52 of the brushes 62 and 63 supported from the frame 50 bymeans of a block of insulation material 64 and connected to theterminals 33 and 40, respectively, the brush 62 being in continuousengagement with the contact segment 61 and the brush 63 normally beingout of engagement there with. Also co-operating with the contactsegment61 is" an adjustable stationary contact brush 65 mounted on ablock of insulation material 66 secured to an angularly adjustable crankarm 6'7 having a hub 68 rotatable on the shaft 46. The. fixed contact 63and the adjustable.

contact 65 comprise a pair of spaced contacts which are of; contacts tovary the time spacing of the developed elec-" v Co-operating with thecontact segment 61 is a stationary electric con tact means including apair of stationary or fixed contact normally out of engagement with, butare engaged in sequence by, the rotatable contact segment 61.Specifically, upon rotation of the inertia wheel 45 when released by theelectromagnet 57, it will be noticed that the conductive segment 61initially makes contact with the movable contact brush 65 andsubsequently with the fixed contact brush 63, the contact segment 61being continuously in contact with brush 62. Thus, the contact brushes63 and 65 are spaced physically to produce timespaced electricalimpulses upon rotation of the inertia wheel 45.

The precision timer also includes means for adjusting the spacing of thecontacts 63 and 65 to vary the time spacing of the electrical impulses,and thus the exposure period of the shutter mechanism controlled by thetimer, preferably as a logarithmic function of the adjusting member.This adjusting means may be in the form of a manually rotatableadjusting element or knob 69 mounted on a shaft 70 and connected to saidbrush 65 through a linkage including a pair of spur gears 71, 72 and ashaft 73 carrying a crank arm 74. The crank 74 is pivoted to one end ofa link 75, the other end of which is pivoted to a crank 76 secured tothe hub 68 to which the arm 67 is also secured. The linkage comprisingelements 74, 75, and 76 are empirically proportioned to provide a timespacing of the output pulses which varies approximately as the logarithmof the angular displacement of the knob 69 and input shaft 70 over amajor portion of its range of adjustment. Knob 69 is provided with apointer 69a co-operating with a scale 69!), which may be calibrated toindicate camera exposure time, as explained hereinafter.

The precision timer of the invention may be utilized to control theexposure time of a two section camera shutter by providing a controlcircuit schematically represented in the drawing. Specifically, thiscircuit cornprises a pair of supply terminals 36, 37, the terminal 36being connected through a switch 41 to an input terminal 38 connected tothe brush 62 of the timer. It is understood that the switch 41represents any suitable means, manual or automatic, for supplying to thetimer a single tripping or triggering pulse of a duration equal at leastto the maximum camera exposure. The timer also is provided with outputterminals 39, 40 connected to the brushes 63, 65 of the timer, thespaced electrical output pulses appearing between the terminals 38, 39and 38, 40. The terminals 39, 40 are connected to correspondingterminals of actuating electromagnets 31, 34, the other terminals ofwhich are connected in common to supply terminal 37. The electromagnets31, 34 are provided with armatures 31b, 34b connected to shutter sectionA and shutter section B, respectively, of a two-section camera shutter,as described in aforesaid copending application, Serial No. 340,557. Theelectromagnet 57 is also connected to be energized from the supplyterminals 36, 37 through switch 41.

In brief, the operation of the timer is initiated by closing of theswitch 41 to energize the rotary electromagnet 57. The magnet armature58 is rotated counterclockwise driving shaft 54 and winding spring 53,its arm 58b subsequently tripping the latch 48 to release the arm 47 ofthe inertia Wheel 45. The wheel 45 then rotates clockwise under theinfluence of its spring 53 and, in so doing, makes successive contactsbetween the contact segment 61 and the contact brushes 65 and 63,thereby developing time-spaced electrical impulses at the terminals 39,40, respectively. By adjustment of the knob 69, the angular position ofthe arm 67 carrying the contact 65 may be adjusted to vary the spacingbetween the stationary contact brush 63 and the movable contact brush65. Upon tripping of the latch 48, as described, the spring 53accelerates the inertia wheel 45 so that its velocity progressivelyincreases throughout its range of movement but follows the same law ofvariation under 7 all operating conditions. Therefore, the time spacingof electrical impulses so generated varies in correspondence with theangular spacing of the contact brushes 63 and 65 so that the scale 69bassociated with the knob 69 may be calibrated directly in terms ofcamera exposure time. The relationship of parts is such that the minimumtime spacing of the electrical impulses corresponds to an angularposition of movable brush 65 such that the timing is determined by thefinal and highest velocity portion of the range of movement of theinertia Wheel 45, thus facilitating the setting of the mechanism forminimum camera exposures with the greatest precision. When theelectromagnet is de-energized, its biasing spring (not shown) returns itto the position illustrated and in so doing resets the inertia disc 45with its arm 47 behind the latch 48.

In the operation of the timer, as described above, it is effective toactuate the shutter sections A and B in sequence with a time spacingdependent upon the adjustment of the timer. Upon closing of switch 41the electromagnet 57 is energized to initiate operation of the timer, asdescribed. At a time dependent upon the setting of the brush 65 by theknob 69, the movable contact segment 61 engages the brush 65 anddevelops an initial electric pulse at the output terminal 39. This pulseenergizes the electromagnet 31 which actuates the shutter section A toinitiate the exposure. A predetermined time interval thereafter thecontact segment 61 engages the stationary brush 63 to develop at theoutput terminal 40 a second electric pulse for energizing theelectromagnet 34 to actuate the shutter section B and complete thecamera exposure. This cycle of operation may be repeated for effectingsubsequent exposures by supplying further single triggering pulses bymeans of the supply terminals 36, 37 and the switch 41, or equivalent.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention, and it is, therefore,aimed in the appended claims to cover all such changes and modificationsas fall within the true spirit and scope of the invention.

What is claimed is:

l. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: first electriccontact means; second electric contact means co-operating with saidfirst contact means and relatively movable with respect thereto, one ofsaid contact means including a pair of spaced contacts; means forimparting a predetermined acceleration to said relatively movablecontact means throughout the range of relative movement for developingtime-spaced electrical pulses; and means for adjusting the spacing ofsaid pair of contacts to vary the time spacing of the developedelectrical pulses.

2. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: movable electriccontact means; stationary electric contacts means co-operating with saidmovable contact means, one of said contact means including a pair ofspaced contacts; means for imparting a predetermined acceleration tosaid movable contact means throughout its range of movement fordeveloping time-spaced electrical pulses; and means for adjusting thespacing of said pair of contacts to vary the time spacing of thedeveloped electrical pulses.

3. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: an inertiamember having movable electric contact means; stationary electriccontact means co-operating with said movable contact means, one of saidcontact means including a pair of spaced contacts; means includ- 5 ing abiasing spring and a latch for said inertia member to impart apredetermined acceleration to said movable contact means throughout itsrange of movement for developing time-spaced electrical pulses; andmeans for adjusting the spacing of said pair of contacts to vary thetime spacing of the developed electrical pulses.

4. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: au inertia dischaving movable electric contact means; stationary electric contact meansco-operating with said movable contact means, one of said contact meansincluding a pair of spaced contacts; means including a biasing springand a latch for said inertia disc to impart a predetermined accelerationto said movable con-- tact means throughout its range of movement fordeveloping time-spaced electrical pulses; and means for adjusting thespacing of said pair of contacts to vary the time spacing of thedeveloped electrical pulses.

5. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: a rotatableinertia member having movable electric contact means; stationaryelectric contact means co-operating with said movable contact means, oneof said contact means including a pair of spaced contacts; a spring forbiasing said inertia member for rotation throughout its range ofmovement; a latch for restraining said inertia member; means responsiveto a tripping effect for releasing said latch to impart a predeterminedacceleration to said movable contact means throughout its range ofmovement for developing time-spaced electrical pulses; and means foradjusting the spacing of said pair of contacts to vary the time spacingof the developed electrical pulses.

6. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: a rotatableinertia member having movable electric contact means; stationaryelectric contact means co operating with said movable contact means, oneof said contact means including a pair of spaced contacts; a spring forbiasing said inertia member for rotation throughout its range ofmovement; a latch for restraining said inertia member; arotatable-armature electromagnet responsive to a tripping signal forWinding said spring and for releasing said latch to impart apredetermined acceleration to said movable contact means throughout itsrange of movement for developing time-spaced electrical pulses; andmeans for adjusting the spacing of said pair of contacts to vary thetime spacing of the developed electrical pulses.

7. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: a movablecontact segment; stationary electric contact means including a fixedcontact in continuous engagement with said segment and a pair of spacedcontacts normally out of engagement with said segment; means throughoutits range of movement for imparting a predetermined acceleration to saidmovable contact segment throughout its range of movement to engage saidpair of contacts in succession for developing timespaced electricalpulses; and means for adjusting the spac- 6 ing of said pair of contactsto vary the time spacing of the developed electrical pulses.

8. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: a movablecontact segment; stationary electric contact means including a pair offixed contact brushes, one in continuous engagement with said segmentand one normally disengaged therefrom, and an adjustable contact brushnormally disengaged from said segment; means for imparting apredetermined acceleration to said movaole contact segment throughoutits range of movement to engage said normally disengaged contact brushesin succession for developing time-spaced electrical pulses; and meansfor adjusting said adjustable brush to vary the time spacing of thedeveloped electrical pulses.

9. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: a movablecontact segment; stationary electric contact means including a pair offixed contact brushes, one in continuous engagement with said segmentand one normally disengaged therefrom, and an adjustable contact brushnormally disengaged from said segment; means for imparting apredetermined acceleration to said movable contact segment throughoutits range of movement to engage said adjustable contact brush and saidnormally disengaged fixed brush in sequence for developing time-spacedelectrical pulses; and means for adjusting said adjustable brush to varythe time spacing of the developed electrical pulses, whereby the minimumtime spacing of the developed pulses corresponds to a position of saidadjustable brush such that the timing is determined by the highestvelocity portion of the range of movement of said movable segment.

10. A precision electromechanical timer for developing a pair ofelectrical pulses adjustably spaced in time comprising: movable electriccontact means; stationary electric contact means co-operating with saidmovable contact means and including a fixed contact and an ad justablecontact; means for imparting a predetermined acceleration to saidmovable contact means throughout its range of movement for developingtime-spaced elec trical pulses; and means for adjusting said adjustablecontact to vary the time spacing of the developed electrical pulsesincluding a manually rotatable adjusting element and a mechanicallinkage interconnecting said element and said adjustable contact forimparting an approximately logarithmic function to the adjustment-timespacing characteristic of the timer.

References Cited in the file of this patent UNITED STATES PATENTS673,274 Leonard Apr. 30, 1901 1,494,986 Behm May 20, 1924 1,969,926Eickhotf Aug. 14, 1934 2,547,199 Dezzani Apr. 3, 1951 2,608,625 RieszAug. 26, 1952

